Glue gun



FIG. 1 is a rear left perspective view of the present new design for a glue gun;

FIG. 2 is a left elevational view thereof;

FIG. 3 is a right elevational view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines showing various features of a glue gun are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for a glue gun, as shown and described. 